Assertion (A): Atomic mass has no units.
Reason ( R): Atomic mass is an expression of ratio.

Assertion (A): Atomic mass of potassium is 39. Reason (R ): An atom of postassium is 39 times heavier than 1//2th of the mass of carbon atom (C^(12)) .

Assertion (A): Atomic mass of potassium is 39. Reason (R ): An atom of postassium is 39 times heavier than 1//2th of the mass of carbon atom (C^(12)) .

The unit of atomic mass is :

Define atomic mass unit.

Define atomic mass unit.